Q: When and how do I store my dahlias to hold over for next spring. Jack, Tilbury

A: The best time to dig your dahlias is after the first hard frost of fall.

The plants will blacken, now cut off the stalks to about 15 centimetres (six inches) above the ground. Leave your clumps in the ground for at least a week before digging. This will make the eyes develop and will make dividing easier.

Use garden fork or a shovel to dig your dahlias, Shovels work much better in heavy, or wet soils; garden forks are better for dry sandy soils. Many people cut off the ends of long tubers anyway to make them easier to store.

Dig down on all four sides about a foot away and lift clumps carefully to avoid breaking the necks of any long or thin-necked tubers. Wash the excess dirt from the clumps with a garden hose and trim off all feeder roots (long tapered roots at the tuber ends).

Tag or label your clumps to keep track of the variety. Do not leave them in the sun, and allow the clumps to dry overnight in a cool dry location.

Use a sharp knife to divide your clumps. The first step in dividing your clump is to remove all easy-to-separate tubers. Your tubers are now ready for storage.

Also, to prevent the spread of virus, clean your tools with alcohol before going on to divide the next clump. Soak the divided tubers in a bleach solution (one cup bleach to three gallons of water) for 15 or 20 minutes. This solution will kill any fungus or bacteria that might be attached on any of the tubers; this will prevent its spread during storage.

Place all of the tubers you get from one clump or from one variety into a plastic pot containing your bleach solution. After 15 or 20 minutes, remove the pot, let the water drain back to reuse.

Let the tubers dry for a few minutes and while they are still slightly damp, write the name of the variety on each tuber.

After your dahlia tubers have completely dried for a day or two, place them in cardboard boxes or plastic bins lined with coarse vermiculite, sawdust, sand or potting soil mix. Store in a dry, cool place until spring. Use layers of newspapers for added insulation, if necessary.

It’s very important that your storage area does not freeze. The ideal temperature for stored dahlias is 40-45 F. Check on your stored tubers once a month to make sure they are not rotting or shrivelling. If they seem too moist then repack with drier material. If they are drying out, spray a little water into the tubers and medium. Any rotting material should be removed immediately.

The ideal storage location would be an old root cellar. Most of us, however, will have to make due with a less efficient location. The crawl space under the house, an unheated but insulated garage or even a corner of frost-free garage will do.

Compiled by master gardeners Alan and Karen Batke. Send a question to the Master Gardener hotline, 519-561-6328, or email to essexwindsor@mastergardeners.fastmail.fm

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